Systems and methods for non-rigid load vibration control

ABSTRACT

A system includes a motor configured to be coupled to a non-rigid load and a control system disposed within, or communicatively coupled to, a drive system configured to control an operation of the motor. The control system includes a processor and a memory accessible by the processor. The memory stores instructions that, when executed by the processor, cause the processor to generate a smooth move input profile to control the operation of the motor based on inputs specifying a desired operation of the motor, apply a notch filter having a notch filter frequency to the smooth move input profile to produce a filtered smooth move input profile, and send a command to the drive system based on the filtered smooth move input profile, wherein the command is configured to adjust the operation of the motor.

BACKGROUND

The present disclosure relates generally to motor control. Morespecifically, the present disclosure relates to controlling motorscoupled to non-rigid loads.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present techniques,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Motors or other actuators are used in many different applications tomove non-rigid loads. These non-rigid loads may include, for example, amass suspended by a cable (e.g., crane and hoist), a load coupled by abelt or long shaft, a cantilevered load, a tank or other vessel carryinga liquid, an end effector of a robot, or an otherwise flexible objectsusceptible to vibration, resonance, or other movement in response tomovement by the motor. Even tightly controlled motors may cause loads tomove in an undesirable fashion. Accordingly, improved techniques forreducing movement of non-rigid loads are needed.

BRIEF DESCRIPTION

In one embodiment, a system includes a motor configured to be coupled toa non-rigid load and a control system communicatively coupled to a drivesystem configured to control an operation of the motor. The controlsystem includes a processor and a memory accessible by the processor.The memory stores instructions that, when executed by the processor,cause the processor to generate a smooth move input profile to controlthe operation of the motor based on inputs specifying a desiredoperation of the motor, apply a notch filter having a notch filterfrequency to the smooth move input profile to produce a filtered smoothmove input profile, and send a command to the drive system based on thefiltered smooth move input profile, wherein the command is configured toadjust the operation of the motor.

In another embodiment, a non-transitory, tangible, computer readablemedium includes instructions that, when executed by a processor, causesthe processor to receive inputs specifying a desired operation of amotor, wherein the motor is communicatively coupled to a drive systemand configured to be coupled to a non-rigid load, generate a smooth moveinput profile to control the operation of the motor based on the inputsspecifying the desired operation of the motor, apply a notch filterhaving a notch filter frequency to the smooth move input profile toproduce a filtered smooth move input profile, and send a command to thedrive system based on the filtered smooth move input profile, whereinthe command is configured to adjust the operation of the motor.

In yet another embodiment, a method includes steps of generating, via acontrol system, a smooth move input profile to control actuation of amotor coupled to a non-rigid load based on inputs specifying a desiredoperation of the motor, applying, via the control system, a notch filterhaving a notch filter frequency to the smooth move input profile toproduce a filtered smooth move input profile, and sending, via thecontrol system, a command to a drive system based on the filtered smoothmove input profile, wherein the command is configured to adjust theoperation of the motor.

DRAWINGS

These and other features, aspects, and advantages of the presentembodiments will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 illustrates a block diagram of a high-level overview of anindustrial system, in accordance with embodiments presented herein;

FIG. 2 is a schematic of a compliant two mass system, which can be usedto model the system shown in FIG. 1, in accordance with embodimentspresented herein;

FIG. 3 illustrates a velocity control loop for the system shown in FIG.1 that utilizes the compliant two mass system shown in FIG. 2 to modelmotor side resonances and load side resonances in the system shown inFIG. 1, in accordance with embodiments presented herein;

FIG. 4 is a control loop diagram illustrating an open loop approach toreducing resonance in a closed loop system, in accordance withembodiments presented herein;

FIG. 5 illustrates first, second, and third derivatives for severaldifferent input functions, in accordance with embodiments presentedherein;

FIG. 6 illustrates a schematic of an embodiment of a discrete secondorder notch filter, in accordance with embodiments presented herein;

FIG. 7 is a control loop diagram illustrating a closed loop approach toreducing resonance in the closed loop system shown in FIG. 4, inaccordance with embodiments presented herein; and

FIG. 8 is a flow chart of a process for reducing resonance of anon-rigid load, in accordance with embodiments presented herein.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Motors are frequently used to move non-rigid loads. These configurationsmay include, but are not limited to, a mass suspended by a cable (e.g.,crane and hoist), a load coupled to another object by a belt or longshaft, a cantilevered load, a tank or other vessel carrying a volume ofliquid, an end effector of a robot, or an otherwise flexible object.Sharp movements by the motor and/or inputs at the resonant frequency ofthe load may cause the load to sway, slosh, resonate, vibrate, orotherwise move in an undesirable fashion. Even tightly controlled motorsmay excite the load at the resonant frequency, causing undesirablemovement of the load. In response, some operators may de-tune motors toreduce vibration at the resonant frequency. For example, an operator mayreduce a gain setting of a proportional-integral (PI) controller toproduce a lower bandwidth control signal, controlling the motor at aslower rate, and thus avoiding excitation at the resonant frequency ofthe system. However, detuning a motor can compromise the motor'sperformance.

The disclosed techniques include utilize “smooth move” input profilesand a notch filter to control actuation of the motor. Smooth move inputprofiles, also referred to as command profiles and/or referenceprofiles, are input profiles having at least second derivatives that arepiece-wise continuous. In some embodiments, smooth move input profilesmay have third, fourth, fifth, and so on derivatives that are piece-wisecontinuous. For example, a smooth move input profile may include a cubicfunction, a 5th order polynomial function, a 7th order polynomialfunction, a sinusoidal function, a modified sine function, a sinesquared function, etc. By implementing smooth move input profiles, themotor may move according to a smooth and steady function. The piece-wisecontinuity avoids steps that generate harmonics to excite motor and loadresonances. The notch filter removes components of the input signalwithin a specified range of frequencies. The notch filter is defined bya notch frequency, a notch width, a notch depth, and a gain. The notchfrequency defines the central frequency that the notch filter removes.The notch width defines the range of frequencies removed by the notchfilter, which is centered at the notch frequency. The notch depthdefines the amplitude removed within the range of frequencies defined bythe notch frequency and the notch width. The gain is a ratio of theoutput of the filter to the input to the filter. By setting the notchfrequency to the resonant frequency of the load, the notch filterremoves parts of the input signal that are likely to excite the load atthe resonant frequency and cause movement of the load. In some cases,the non-rigid load vibration control system may operate in an open loopconfiguration with just the smooth move input profile and the notchfilter, with no feedback loop from the load. However, in otherembodiments, the non-rigid load vibration control system may operate ina closed loop configuration, using a sensor to collect datacorresponding to the load during actuation of the motor. In such anembodiment, the control system may generate a supplemental input signalbased on the collected data, via an auxiliary feedback loop, and/or withan adjustable integral gain. In some embodiments, the supplemental inputsignal may be conditioned by a proportional integral (PI) process block.

Using the smooth move input profile and a notch filter in conjunctionwith one another may reduce sharp movements by the motor, as well asreducing excitation of the load at the resonant frequency. Smoothmovements (e.g., movements based on input profiles having at leastsecond derivatives that are piece-wise continuous) by the motor andinput profiles having reduced amplitudes at the resonant frequency ofthe load reduce unwanted an unpredictable movement, vibration, andresonance of the load, resulting in smooth and predictable load behaviorduring actuation of the motor.

By way of introduction, FIG. 1 is a perspective view of a system 10,including a power source 12, a motor drive system 13, which includes acontrol system 14 and a power converter 15, a motor 16, and a complianton non-rigid load 18. In the instant embodiment, the system 10 is anindustrial automation system 10 having one or more motor drive systems13 coupled to one or more motors 16, which are then coupled to one ormore compliant loads 18. In such an embodiment, the motor drive includesthe control system 14 and the power converter 15. The control system 14,which may be used to control the motor drive systems 13, may includevarious subcomponents, such as a non-transitory memory 22, a processor24, a user interface, and the like. The power converter 15 may beconfigured to condition the power signal output by the control system14. For example, the power converter 15 may be configured to convert asignal from alternating current (AC) to direct current (DC), convert asignal from DC to AC, step a signal up, step a signal down, etc. Themotor drive system 13 may also include various subcomponents, such as arectifier, an inverter, driver circuitry, one or more switches, etc.,that may be used to control the operation of the motor 16. The powersource 12 may supply a regular voltage or high voltage alternatingcurrent (AC) signal provided by a utility power grid (e.g., a standardelectrical outlet), a battery, a capacitor, a generator, or some othersource of AC or direct current (DC) electrical power. However, it shouldbe understood that many possible embodiments are envisaged. For example,the control system 14 may be any component configured to output acontrol signal (directly or indirectly) to the motor 16 or actuator inorder to cause the actuator to move. Accordingly, the motor 16 may havemechanical and/or electrical components and may include a linear motor,a servo, a rotational electric motor, a combustion engine, a trolley, amover, or any other component configured to move in response to acontrol signal. The load 18 may be any compliant load, meaning that theload itself may be compliant, may be coupled to the motor via acompliant linkage 20, or may otherwise be capable of movement in one ormore directions. For example, the load 18 may be a mass suspended by acable (e.g., crane and hoist), a load coupled by a belt or long shaft, acantilevered load, a tank carrying a liquid, an end effector of a robot,or otherwise flexible object susceptible to movement in response tomovement by the motor 16. In some embodiments, the system 10 may includesensors 26 disposed on the motor (e.g., an encoder), on the load 18, orboth. The sensors 26 may be in communication with the control system 14and providing measurements to the control system 14, which the controlsystem 14 may utilize to generate control signals.

In some cases, because of the compliant nature of the load 18,controlled movement of the motor 16 may result in swaying, oscillation,vibration, sloshing, or other unwanted movement of the load 18.Accordingly, the system 10 can generally be modeled as a compliant twomass system. FIG. 2 is a schematic of a compliant two mass system 100,which can be used to model the mechanical aspect of the motor 16 and theload 18 within the system 10 shown in FIG. 1 as a rotating machine.However, it should be understood that models for crane and hoistconfigurations, liquid slosh, robot end effectors, etc. are similar. Asshown, the two mass system 100 includes a first mass 102 and a secondmass 104, coupled to one another by a spring 106. The motor 16 providesan input via a shaft 108 and the load 18, represented by the first mass102, the second mass 104, and the spring 106, responds. As shown in FIG.2, the motor 16 provides a motor torque, T_(M), and rotates the shaft108 at a motor velocity, V_(M). The moment of inertia of the motor 16 isrepresented by J_(M) and the angular displacement of the motor 16 isrepresented by s. T_(R) represents the reaction torque on the shaft 108from the first mass 102. The viscous friction is represented by b and krepresents the spring constant of the spring 106. The second mass 104rotates at a load velocity, V_(L). The moment of inertia of the load 18is represented by J_(L). The load torque disturbance is represented byT_(D). The two mass system 100 model shown in FIG. 2 can be used todetermine motor side resonances and load side resonances of the system10 shown in FIG. 1 in response to movement by the motor 16.

FIG. 3 illustrates a velocity control loop 200 for the system 10 shownin FIG. 1 that utilizes the compliant two mass system 100 shown in FIG.2 to model motor side resonances and load side resonances in the system10. As shown, a PI controller 202 outputs a control signal to a powerconverter 204, which converts and/or conditions the control signal andoutputs the modified control signal to the motor 16. The motor sideresonances, plotted in the motor side resonances bode diagram 206 may bedetermined by the transfer function:

$\begin{matrix}{{{{motor}\mspace{14mu}{side}\mspace{14mu}{resonances}} = \frac{{J_{L}s^{2}} + {bs} + k}{{J_{E}s^{2}} + {bs} + k}},} & (1)\end{matrix}$wherein, J_(E) is defined as:

$\begin{matrix}{J_{E} = {\frac{J_{L} \cdot J_{M}}{J_{L} + J_{M}}.}} & (2)\end{matrix}$

Similarly, the load side resonances, plotted in the load side resonancesbode diagram 208 may be determined by the transfer function:

$\begin{matrix}{{{load}\mspace{14mu}{side}\mspace{14mu}{resonances}} = {\frac{{bs} + k}{{J_{L}s^{2}} + {bs} + k}.}} & (3)\end{matrix}$

As illustrated in FIG. 3, the motor velocity, V_(M), may be measured(e.g., via an encoder) and passed through a low pass filter 210, and fedback to the PI controller along with a command velocity, V_(CMD). Asshown in the respective bode diagrams, both the motor 16 and the load 18resonate at specific frequencies. Accordingly, steps may be taken toreduce the resonance of the system 10. Specifically, the combination ofa “smooth move” input profile and a notch filter may be used to reducethe resonances of within the system 10.

FIG. 4 is a control loop diagram 300 illustrating an open loop approachto reducing resonance in a closed loop system 302. As shown, the closedloop system 302 may include one or more feedback loops 304 in which oneor more measurements taken within the system (e.g., y_(M)) are comparedto one or more set points (e.g., r) by one or more control blocks 306and/or one or more process blocks 308. As shown, the closed loop controlsystem 302 may cause the load to resonate at some resonant frequency L310, which can be measured or otherwise determined. To reduce resonanceat the resonant frequency, a notch filter 312 may be applied to theinput signal before providing the input signal to the closed loop system302. Historically, notch filters have been disfavored in conditioninginput command signals for load control applications. Instead,technologies such as input shaping have generally been preferred overnotch filters in the industry for addressing load resonance. As isdescribed in more detail below, one or more parameters of the notchfilter (e.g. the frequency of the notch filter, the width of the notchfilter, the depth of the notch filter 312, the gain of the notch filter,etc.) may be customizable. Because the notch filter 312 is inapplication an inverse of resonance, removing a range of frequenciesfrom vibration, the value of the notch filter 312 may be set at aninverse of the load side resonance transfer function (e.g., L⁻¹). Byremoving a range of frequencies around a resonant frequency, L 310, froman input signal, excitation, and thus, resonance at the resonantfrequency, L 310, is reduced.

In addition to the notch filter 312, “smooth move” input profiles 314may be used instead of traditional linear or otherwise discontinuousinput profiles. Smooth move profiles 314 may include input profiles formotors that do not include steps, jumps, or other discontinuities in theacceleration of a motor or actuator. Put another way, smooth moveprofiles 314 are profiles that are piece-wise continuous to the n^(th)derivative of the input profile. For example, the smooth move inputprofiles 314 may include, for example, a cubic function, a 5th orderpolynomial function, a 7th order polynomial function, a sinusoidalfunction, a modified sine function, an adjusted sine function, a sinesquared function, a cyclosoidal function, a sine-constant-cosine (SCCA)function, a simple harmonic motion, and so forth. The use of smooth moveinput profiles 314 may further reduce unwanted vibration, resonance,and/or movement within a system 302.

FIG. 5 illustrates first, second, and third derivatives for severaldifferent input functions. The first row 400 includes, from left toright, first, second, and third derivatives of a trapezoidal inputfunction. The first derivative of the trapezoidal input function isrepresentative of velocity of the motor and/or load. As shown in FIG. 5,the first derivative of the trapezoidal input function is piece-wisecontinuous in the first derivative because the graph of the firstderivative does not include any steps or jumps (e.g., instantaneouschanges in displacement, velocity, acceleration, etc. at a given momentin time). Steps create harmonics (e.g., the Fourier transform of asquare wave) which excite motor and load resonances. However, as shownin FIG. 5, the graphs of the second and third derivatives of thetrapezoidal input function do include steps, so the trapezoidal inputfunction is not piece-wise continuous in the second or third derivative.Accordingly, the trapezoidal input function is considered to be “Clcontinuous” (i.e., only the first derivative is continuous) and is notconsidered a smooth move input profile. However, the graphs of thevarious derivatives of the 5^(th) order polynomial input function shownin the second row 402 do not include any steps or jumps, so the 5^(th)order polynomial input function is piece-wise continuous in the first,second, and third derivatives. Similarly, the graphs of the variousderivatives of the sine squared input function shown in the third row404 do not include any steps or jumps, so the sine squared inputfunction is piece-wise continuous in the first, second, and thirdderivatives. Accordingly, the 5^(th) order polynomial input function andthe sine squared input function would be considered smooth move inputfunctions. It should be understood, however, that these examples are notintended to be limiting and that other input profiles that arepiece-wise continuous to a specified derivative may be considered smoothmove profiles.

FIG. 6 is a schematic of an embodiment of the notch filter 312,illustrated as a discrete second order notch filter 312. However, itshould be understood that that the discrete second order notch filter312 shown in FIG. 6 is merely an example and that use of other notchfilters is also envisaged. As shown, the notch filter 312 includes firstand second delay elements 500. The continuous-time transfer function ofthe notch filter 312 is represented by the following equation:

$\begin{matrix}{{{F(s)} = {\frac{y(s)}{u(s)} = \frac{{k^{2}s^{2}} + {4\pi\; k\;\zeta_{d}{fs}} + \left( {2\pi\; f} \right)^{2}}{s^{2} + {4{\pi\zeta}_{w}{fs}} + \left( {2\pi\; f} \right)^{2}}}},} & (4)\end{matrix}$wherein s is the angular displacement, f is the notch frequency in unitsof Hz, ζ_(w) is the notch width, ζ_(D) is the notch depth, and k is thegain. In the instant embodiment, the notch filter 312 may be provided toa customer with one or more default settings in order to easeinstallation for the customer. For example, the default value for notchwidth may be 0.707, the default value to notch depth may be 0, and thedefault value for gain may be 1. These default values may be determinedto achieve broad applicability in the widest range of applications.Accordingly, the customer may only have to set the notch frequency inorder to start using the notch filter 312. However, the customer maystray from the default settings in order to fine tune the notch filter312 to the specific application being implemented.

Returning to the control loop diagram 300 of FIG. 4, it should beunderstood that the closed loop system 302 shown is merely an exampleand a place holder for any open or closed loop system to which thedisclosed techniques may be applied. That is, the notch filter 312 andsmooth move input profiles 314 may be applied to many other controlsystems. Further, the control loop diagram 300 shown in FIG. 4represents an open-loop approach because there is no feedback loop basedon a measurement taken at the load. For most customers, the open loopapproach shown in FIG. 4 will perform adequately such that thesimplicity of an open loop approach outweighs the improved performance,but added complexity, of a closed loop approach. However, in someembodiments, an outside disturbance (e.g., wind or picking a load up offcenter, creating non-zero initial conditions) may make an applicationbetter suited to the improved performance of a closed loop approach,despite the added complexity.

FIG. 7 is a control loop diagram 600 illustrating a closed loop approachto reducing resonance in a closed loop system 302. As shown, adisturbance 602 (e.g., wind or some other outside force, illustrated asT_(D) in FIG. 2 for rotating loads) may be applied to the load,resulting in unwanted vibration, resonance, or movement of the load.Accordingly, the control loop diagram 600 includes a feedback loop 604(e.g., based on a measurement on or near the load from a sensor). Thefeedback loop may run through a proportional integral (PI) process block608 before being input to the closed loop system 302 as a supplementalinput signal 612. In some embodiments, the system may also include asingle input (e.g., knob) integral gain 610, which may be adjusted by auser. Accordingly, the system may utilize measurements take from on oraround the load to adjust the inputs to the closed loop system 302 inorder to account for the disturbance 602 and reduce any unwantedvibration, resonance, or movement.

FIG. 8 is a flow chart of a process 700 for reducing resonance of anon-rigid load 18. At block 702, a smooth move input profile 314 isgenerated based on the desired movement of the motor 16. As previouslydescribed, smooth move profiles 314 are profiles that are piece-wisecontinuous to the n^(th) derivative of the input profile. For example,if the value of n is set to 2, a smooth move profile 314 is an inputprofile that does not include steps, jumps, or other discontinuities inthe acceleration (i.e., second derivative of position) of the motor 16or actuator. Smooth move profiles 314 may include, for example, cubic,5^(th) order polynomial, 7^(th) order polynomial, sinusoidal, modifiedsine, adjusted sine, sine squared, cyclosoidal, sine-constant-cosine(SCCA) functions, simple harmonic motion, etc.

At block 704, a notch filter 312 is applied to the generated smooth moveprofile 314. The notch filter 312 removes a range of frequencies fromthe smooth move profile 314. The notch filter 312 may be defined bymultiple parameters, which may include, for example, notch frequency,notch width, notch depth, and gain. The notch frequency defines thecentral frequency that the notch filter 312 removes. The notch widthdefines the range of frequencies removed by the notch filter 312, whichis centered at the notch frequency. The notch depth defines theamplitude removed within the range of frequencies defined by the notchfrequency and the notch width. The gain is ratio of the output of thefilter to the input to the notch filter 312. Though each of theparameters may be capable of adjustment by a user, the notch filter 312may be provided with default values for some of the parameters in orderto ease installation and setup. For example, the default value for notchwidth may be 0.707, the default value to notch depth may be 0, and thedefault value for gain may be 1.

At block 706, the filtered input profile 314 is provided to the system302. In some embodiments, the filtered input profile 314 is provided toa control system 13 of the system, which may further condition thesignal before providing the signal to the motor 16. In otherembodiments, however, the filtered input profile 314 may be provideddirectly to the motor 16. The motor 16 may then extend, contract,rotate, or otherwise actuate based on the filtered input profile 314.

At block 708, if a closed loop, non-rigid load vibration controlconfiguration is being implemented, a sensor 26 may collect data fromthe load 18. For example, the sensor 26 may collect data regardingposition, velocity, acceleration, vibration, oscillation, etc. of theload, a shaft, a part of the motor, etc. However, if an open loop loadvibration control configuration is being implemented, measurements maynot be collected from the load 18 and block 708 may be omitted.

At block 710, an adjustment to an integral gain 610 may be received froma user via a user interface component. As discussed with regard to FIG.7, some embodiments of the non-rigid load vibration control system mayinclude an integral gain 610, while other embodiments of the non-rigidload vibration control system may omit an integral gain 610. Forexample, closed loop embodiments of the non-rigid load vibration controlsystem may include an integral gain 610 and open loop embodiments of thenon-rigid load vibration control system may omit an integral gain 610.Accordingly, if the non-rigid load vibration control system does nothave an integral gain control 610, block 710 may be omitted. Forembodiments of the non-rigid load vibration control system that includean integral gain 610, the integral gain may be a single user interfaceelement (e.g., a rotating knob, slider, etc.) that allows the user tocontrol the gain.

At block 712, a supplemental input signal 612 is provided to the system302 based on the measurement collected in block 708 and/or the gainadjustment received in block 710. As shown and described with regard toFIG. 7, in some embodiments, the feedback signal 604 may be run througha process block 608 (e.g., a PI process block) before being provided tothe system 302 as the supplemental input signal 612. In someembodiments, the supplemental input signal 612 may be provided alongwith the filtered input profile signal 314 at the same point in thesystem 302. In other embodiments, as shown in FIG. 7, the supplementalinput signal 612 may be provided to a different point within the system302 than the filtered input profile signal 314. The system 302 may thencontinue to run based on the supplemental input signal 612 and thefiltered input profile signal 314.

At block 714, inputs adjusting one or more of the notch filterparameters may be received to fine tune the notch filter 312. Aspreviously described, the notch filter parameters may include notchfrequency, notch width, notch depth, and gain. The notch filter 312 maybe shipped with various default settings to one or more of theparameters. However, if the user wishes to fine tune the notch filter312 by making adjustments to the existing parameters, the user mayprovide inputs making adjustments to one or more of the notch filterparameters. The system may then return to block 704 and implement theadjustments to the notch filter parameters and continue operating withthe adjusted notch filter parameters.

The disclosed techniques include utilizing “smooth move” input profilesand a notch filter to control actuation of a motor coupled to anon-rigid load. Smooth move input profiles are input profiles having atleast second derivatives that are piece-wise continuous. For example, asmooth move input profile may include a cubic function, a 5th orderpolynomial function, a 7th order polynomial function, a sinusoidalfunction, a modified sine function, a sine squared function, etc. Smoothmove input profiles result is smooth, steady movement of the motor. Thenotch filter removes components of the input signal within a range offrequencies. The notch filter is defined by a notch frequency, a notchwidth, a notch depth, and a gain. The notch frequency defines thecentral frequency that the notch filter removes. The notch width definesthe range of frequencies removed by the notch filter, which is centeredat the notch frequency. The notch depth defines the amplitude removedwithin the range of frequencies defined by the notch frequency and thenotch width. The gain is a ratio of the voltage output by the filter tothe voltage input to the filter. By setting the notch frequency to theresonant frequency of the load, the notch filter removes parts of theinput signal that are likely to excite the load at the resonantfrequency and cause movement of the load. In some cases, the non-rigidload vibration control system may operate in an open loop configurationwith just the smooth move input profile and the notch filter, with nofeedback loop from the load. However, in other embodiments, thenon-rigid load vibration control system may operate in a closed loopconfiguration, using a sensor to collect data corresponding to the loadduring actuation of the motor. In such an embodiment, the control systemmay generate a supplemental input signal based on the collected data,via a feedback loop, and/or an adjustable integral gain input. In someembodiments, the supplemental input signal may be conditioned by aproportional integral (PI) process block.

Using the smooth move input profile and a notch filter in conjunctionwith one another may reduce sharp movements by the motor, as well asreducing excitation of the load at the resonant frequency. Smoothmovements by the motor and input profiles having reduced amplitudes atthe resonant frequency of the load reduce unwanted an unpredictablemovement, vibration, and resonance of the load, resulting in smooth andpredictable load behavior during actuation of the motor.

While only certain features of the present disclosure have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true spirit of the embodiments describedherein.

The invention claimed is:
 1. A system, comprising: a motor configured to be coupled to a non-rigid load via a compliant linkage; a control system disposed within, or communicatively coupled to, a drive system configured to control an operation of the motor, the control system comprising: a processor; and a memory accessible by the processor, the memory storing instructions that, when executed by the processor, cause the processor to: generate a smooth move input profile to control the operation of the motor based on inputs specifying a desired operation of the motor, wherein a second derivative of the smooth move input profile is piece-wise continuous; apply a notch filter to the smooth move input profile to produce a filtered smooth move input profile, wherein the notch filter has a notch filter frequency that is determined based on a resonant frequency of the non-rigid load; and send a command to the drive system based on the filtered smooth move input profile, wherein the command is configured to adjust the operation of the motor.
 2. The system of claim 1, comprising a sensor configured to collect data corresponding to the non-rigid load during the operation of the motor, wherein the control system is configured to generate a supplemental input signal to adjust the operation of the motor based on the collected data.
 3. The system of claim 2, wherein supplemental input signal is conditioned by a proportional integral (PI) process block.
 4. The system of claim 3, wherein the control system comprises a user interface element configured to control an adjustable integral gain of the supplemental input signal.
 5. The system of claim 1, wherein the smooth move input profile comprises a cubic function, a 5th order polynomial function, a 7th order polynomial function, a sinusoidal function, a modified sine function, a sine squared function, or a combination thereof.
 6. The system of claim 1, wherein the notch filter is defined by a notch width, a notch depth, and a gain.
 7. A non-transitory, tangible, computer readable medium comprising instructions that, when executed by a processor, causes the processor to: receive inputs specifying a desired operation of a motor, wherein the motor is communicatively coupled to a drive system and configured to be coupled to a non-rigid load, wherein the non-rigid load comprises a mass suspended by a cable, a vessel carrying fluid, or a combination thereof; generate a smooth move input profile to control the operation of the motor based on the inputs specifying the desired operation of the motor, wherein a second derivative of the smooth move input profile is piece-wise continuous; apply a notch filter to the smooth move input profile to produce a filtered smooth move input profile, wherein the notch filter has a notch filter frequency that is determined based on a resonant frequency of the non-rigid load; and send a command to the drive system based on the filtered smooth move input profile, wherein the command is configured to adjust the operation of the motor.
 8. The computer readable medium of claim 7, wherein the processor is configured to be communicatively coupled to a sensor configured to collect data corresponding to the non-rigid load during actuation of the motor, wherein the processor is configured to generate a supplemental input signal to adjust the operation of the motor based on the collected data.
 9. The computer readable medium of claim 8, wherein supplemental input signal is conditioned by a proportional integral (PI) process block.
 10. The computer readable medium of claim 7, wherein the smooth move input profile comprises a cubic function, a 5th order polynomial function, a 7th order polynomial function, a sinusoidal function, a modified sine function, a sine squared function, or a combination thereof.
 11. The computer readable medium of claim 7, wherein the notch filter is defined by an adjustable notch width, an adjustable notch depth, and an adjustable gain.
 12. A method, comprising: generating, via a control system, a smooth move input profile to control actuation of a motor coupled to a non-rigid load via a compliant linkage based on inputs specifying a desired operation of the motor, wherein a second derivative of the smooth move input profile is piece-wise continuous; applying, via the control system, a notch filter to the smooth move input profile to produce a filtered smooth move input profile, wherein the notch filter has a notch filter frequency that is determined based on a resonant frequency of the non-rigid load; and sending, via the control system, a command to a drive system based on the filtered smooth move input profile, wherein the command is configured to adjust the operation of the motor.
 13. The method of claim 12, comprising: collecting, via a sensor, data corresponding to the non-rigid load during actuation of the motor; generating, via the control system, a supplemental input signal to adjust the operation of the motor based on the collected data; and sending, via the control system, the supplemental input signal to the drive system.
 14. The method of claim 12, wherein the notch filter is defined by an adjustable notch width, an adjustable notch depth, and an adjustable gain. 